and Integrated Pest Management - part - usaid

20
N vrescens moloifty /)
ROLE OF INSECT-RESISTANT VARIlES INRICE IPM SYSTEMS 51
N5,rescens /10 sweeps
50 IR28 Y=24 216 562.t=0 B
A 45- 0
40 R
I0 9
15-- L = 9* n
0 991 *P 252
20 C .3.
IR22
Tungroinfection (')Yid I /ho)
30C
R22 2y0334-2122in.
2 z 090' (n-5)
Dy= R0;17 R*47,=9 2336- n
50
IR22
40 2I2R574 76"'0 99
0 55 1302 33 : :
90- R2-069n,
80 c
70 3 4 200 024
60-r
, 8-134
099(n= 5) 00R 60
50­
401 sl36';i055 T202.
30r R36 100 ra0s 9 2 N
D
* R2:o 0 306s
0 2
Fi. .virescensmotlyanfed pr1 populations wesa 5D,)Pec RTV infection,
Grain yield. (Heinrichs et al. 1986b).
variety had only 10 BPHs per hill whereas susceptible varieties had 1100 per hill
(Aquino and Heinrichs 1979). In cases where the BPH resurges after the
application of insecticide to control the leaffolder, resurgence can be minimized,
providing BPH-resisant varieties are cultivated.
The decreased insecticide requirement of insct resistant varieties conserves
natural enemies, preserves environmental quality, slows rate of selection for
insecticide resistant insect strains, anl increases the profitability of crop
production (Adkinsson nd Dyck 1980). "he incorporation of a resistant variety
D)i